The present invention relates generally to planar optical displays, and, more specifically, to a light projection system therefor.
A thin optical display panel having a plurality of laminated optical waveguides is disclosed in U.S. Pat. No. 5,381,502 over which the present invention is an improvement. Each of the waveguides in the panel includes a transparent core laminated between opposite cladding layers having a lower index of refraction. The waveguides collectively define an inlet face at one end and an outlet face or screen at an opposite end disposed obliquely to the inlet face. The screen forms an extremely small acute face angle with the longitudinal axes of the waveguides, on the order of about 1 or 2 degrees, which allows the height of the screen to be substantially larger than the depth or thickness of the panel for keeping the panel thin.
The thin panel may be used for various applications such as a television video display screen with an exemplary width to height ratio of 4:3 with 525 vertical lines of resolution. This resolution may be simply effected by correspondingly using 525 stacked waveguides which are continuous along the width of the panel. The panel inlet face, therefore, extends the full width of the panel but is extremely narrow corresponding with the thinness of the panel. For example, the thickness of the panel at the inlet face may be about 2.54 cm, with the height of the screen being 100 cm, and a corresponding width of 133 cm. The corresponding thickness of each of the waveguides is about 48 microns.
In the original development of the thin panel, a laser beam was employed to directly produce collimated light which is sequentially scanned laterally and transversely along the inlet face for producing a corresponding image on the screen in the horizontal and vertical directions, respectively. Various types of lenses may be used with the laser beam for ensuring a high resolution image on the screen, but lenses require precise alignment and inherently effect chromatic aberrations which adversely affect the produced image.
Accordingly, it is desired to provide an improved light projector for use with the thin waveguide panel for reducing complexity and cost, and eliminating chromatic aberration.